Field of the Invention
The present invention relates to wireless communication and, more particularly, to a method of receiving acknowledgement/not-acknowledgement (ACK/NACK) in a wireless communication system and an apparatus using the method.
Related Art
In a wireless communication system, a hybrid automatic repeat request (HARQ) may be applied between a transmitter and a receiver. The HARQ is a signal transmission/reception method of checking whether data received in a physical layer includes an error that is unable to be decoded and requesting retransmission when an error occurs. In a process of performing an HARQ, a receiver sends not-acknowledgement (NACK) through a control channel if an error occurs and sends acknowledgement (ACK) through a control channel if an error does not occur. In a prior art, a base station has sent ACK/NACK for data transmitted by a terminal through a channel called a “physical hybrid ARQ indicator channel (PHICH).”
Meanwhile, in the future wireless communication system, a new carrier type (NCT) may be used. The NCT may use a channel structure different from a channel structure used in an existing legacy carrier type (LCT). For example, the NCT may not include a PHICH included in the LCT.
Furthermore, an enhanced-PHICH (E-PHICH) may be used in the existing LCT or the NCT instead of a PHICH. The PHICH is placed in a physical downlink control channel (PDCCH) region, whereas the E-PHICH may be placed outside the PDCCH region.
If a PHICH is not present as in the NCT or ACK/NACK is transmitted through an E-PHICH which may be placed outside the PDCCH region, it is difficult to use a conventional method of sending ACK/NACK through a PHICH without a change.